Flazasulfuron behavior in a soil amended with different organic wastes

Applied Soil Ecology 117–118 (2017) 81–87

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Applied Soil Ecology journal homepage: www.elsevier.com/locate/apsoil

Flazasulfuron behavior in a soil amended with different organic wastes a,⁎

Manuel Tejada , Concepción Benítez

MARK

b

Grupo de investigación “Edafología ambiental”, Departamento de Cristalografía, Mineralogía y Química Agrícola, E.T.S.I.A. Universidad de Sevilla, Crta de Utrera km. 1, 41013 Sevilla, Spain Departamento de Química Agrícola y Edafología, Universidad de Córdoba, Campus de Rabanales, Edificio C-3, Crta N-IV-a, km. 396, 14014 Córdoba, Spain

a

b

A R T I C L E I N F O

A B S T R A C T

Keywords: Flazasulfuron Organic wastes Soil biochemical properties Adsorption Leaching

We studied the flazasulfuron behavior in a soil amended with three organic wastes (municipal solid waste, MSW, poultry manure, PM, and cow manure, CM) and their influence both on its mobility and on the soil’s biochemical properties (soil humus-enzymatic complexes, soil microbial biomass-C and soil ATP). The organic wastes were applied to soil on February 2nd 2014. On June 6th 2014, flazasulfuron was applied. Adsorption and leaching experiments were also performed in soils with herbicide and without and whit organic wastes. Flazasulfuron did not cause changes in soil biochemical properties. Soil biochemical properties were highest in MSW-amended soil, followed by PM and CM. With the MSW amendment, flazasulfuron sorption increased by a factor of 6.7 while for PM and CM, the factor increased 5.8 and 5, respectively. The application of organic matter decreased the soil’s herbicide concentration, possibly due to flazasulfuron sorption by organic matter. The maximum concentration of flazasulfuron in leachates was reduced from 8.9 μM for the unamended soil, to 3.5, 5.4, 6.9 μM for the MSW, PM and CM-amended soils, respectively. Therefore, because decrease the flazasulfuron concentration in leachates, the application to the soil of organic matter with higher humic acid contents is a good environmental practice.

1. Introduction The use of herbicides for weed control is a very common practice in intensive agriculture. However, the continued use of herbicides leads to increase levels of residues of such chemicals in soils and water, with possible negative consequences for public and ecological health (Sørensen et al., 2006; Hiller et al., 2012; López-Piñero et al., 2013). In recent decades, acceptance of the use of herbicides belonging to the sulfonylurea family has become widespread among farmers and scientists concerned with the environment. This wide acceptance is mainly due to sulfonylurea’s ability to provide weed control at doses within the range of 10–40 g grams per ha. Other qualities include: very low acute, chronic animal toxicity (the LD50 in rats are generally > 5000 mg kg−1), a good crop selectivity, and a broad-spectrum weed control (Beyer et al., 1988; Brown, 1990). Furthermore, Fenoll et al. (2013) indicated that because of their favorable environmental properties and low acute mammalian toxicology compared with most other herbicides, sulfonylureas usually provide a large margin of safety with regards to ecological and ecotoxicological effects. Flazasulfuron (N-[4,6-dimethoxypyrimidin-2-yl)-3-(3-trifluoromethyl-2-pyridylsulfonyl)urea]) is an herbicide belonging to the sulfonylurea family which is widely used in the olive oil crop to control wide

⁎

Corresponding author. E-mail address: [email protected] (M. Tejada).

http://dx.doi.org/10.1016/j.apsoil.2017.05.009 Received 22 September 2016; Accepted 11 May 2017 Available online 23 May 2017 0929-1393/ © 2017 Elsevier B.V. All rights reserved.

range of grasses. Both the use of herbicides and the application of organic amendments to agricultural soil is a common farming practice. The application of organic matter to agricultural soil aimed at improving the soil’s physical, chemical and biological properties (Aranda et al., 2015; Li and Han, 2016; Parihar et al., 2016). Moreover, the chemical composition of the organic matter applied to the soil greatly influences the dynamics of the herbicides in soil. In this respect, there is extensive literature indicating that the organic matter applied can adsorb herbicides, thus decreasing their mobility and reducing the possibility of aquifer contamination (Albarrán et al., 2004; López-Piñero et al., 2013). Sorption/desorption is one of the key processes that affect the behavior of agrochemicals in the soil-water environment. They can, therefore, help to understand how to predict the mobility and availability of pesticides in soils (Iglesias et al., 2010). In addition, it also of great environmental importance to know whether soil-applied herbicides might have a toxic effect on soil microorganisms. There are a large number of scientific studies indicating that many herbicides have toxic effects on soil microorganisms (Tejada, 2009; Tejada et al., 2010a,b; Gómez et al., 2014; Franco-Andreu et al., 2016). Therefore, knowledge of this effect, together with the herbicide’s soil mobility, can provide a complete idea of the environmental effect of these chemical com-

Applied Soil Ecology 117–118 (2017) 81–87

M. Tejada, C. Benítez

pounds. Many herbicides are degraded by soil microorganisms. For it, the microorganisms excrete different enzymes into the medium that are responsible for degrading these chemical compounds. However, free enzymes normally have a short-lived activity because they can be rapidly denatured, degraded, or inhibited (Bastida et al., 2008). Enzymes that bind clay and/or humic substances are more resistant to degradation than free enzymes and can persist in soil. Tejada and Benítez (2011) suggested that because immobilized enzymes may act as stable catalysts for the detection of potential substrates. Enzymes immobilized on humus molecules play an important role in soil microbial ecology. Masciandaro et al. (2012) also suggested that their importance arises from the fact they can represent a reservoir of biochemical energy and nutrients. Therefore, studying humus-enzyme complexes could be useful for understanding the herbicide’s toxicity on soil microorganisms. However, despite the widespread use of flazasulfuron, both its behavior in soil and its effects on soil biochemical properties after the application of different sources of organic matter is not known. Therefore, the objective of this study was to investigate the behavior of flazasulfuron in a soil amended with three organic wastes and their influence on its mobility and on the soil’s biochemical properties.

Table 1 Main physico-chemical features of the experimental soil, organic wastes, isolated acidic functional group contents of humic acids and molecular weight proteins distribution from MSW, PM and CM (mean ± standard error). Data are the means of three samples.

pH (H2O) Sand (g kg−1) Silt (g kg−1) Clay (g kg−1) Organic matter (g kg−1) Humic acid-C (mg kg−1) COOH (mol kg−1) Phenolic OH (mol kg−1) Total acidity (mol kg−1) Fulvic acid-C (mg kg−1) Kjeldahl N (g kg−1)

Soil

MSW

PM

CM

7.8 ± 0.2 420 ± 27 247 ± 13 333 ± 19 1.2 ± 0.2 16.5 ± 3.1

6.6 ± 0.3

8.3 ± 0.2

8.0 ± 0.2

466 ± 23 1007 ± 17

622 ± 24 681 ± 17

776 ± 21 466 ± 11

Nd Nd

3.8 ± 0.3 1.6 ± 0.2

3.2 ± 0.1 1.2 ± 0.2

3.0 ± 0.1 1.0 ± 0.1

Nd

5.4 ± 0.3

4.4 ± 0.2

4.0 ± 0.1

9.0 ± 2.0 0.5 ± 0.1

882 ± 20 14.1 ± 2.2

761 ± 25 28.3 ± 2.9

610 ± 16 21.1 ± 1.6

43.6 ± 4.8 24.9 ± 3.0 11.5 ± 2.2 9.2 ± 2.6 10.8 ± 1.7

46.9 ± 3.9 27.8 ± 2.7 9.4 ± 2.9 8.3 ± 2.4 7.6 ± 1.1

48.2 ± 4.5 28.4 ± 3.1 10.6 ± 2.7 7.0 ± 2.4 5.8 ± 1.3

Protein molecular weight (Daltons) > 10000 Nd 10000–5000 Nd 5000–1000 Nd 1000–300 Nd < 300 Nd Nd: Not determined.

2. Material and methods

2.2. Experimental layout

2.1. Characteristics of soil, organic wastes and herbicide

The experimental layout was a randomized, complete block design with eight treatments and three replicates per treatment. The plot size was 7 × 3 m. The organic wastes were surface broadcast on February 2nd 2014 and incorporated to a 25-cm depth by chisel ploughing and disc harrowing. Flazasulfuron herbicide was applied four months after the application of organic wastes to the soil (June 6th 2014). The treatments were the following:

A semiarid soil (0–25 cm surface layer) was collected from an agricultural area located in Córdoba (Spain).The soil is classified as Xerollic Calciorthid (Soil Survey Staff, 1987). Three sources of organic matter were used: a municipal solid waste (MSW), a poultry manure (PM), and a cow manure (CM). Organic wastes were composted under aerobic conditions in a trapezoidal pile (4 m long, 2 m wide and the base and 1 m high) containing approximately 5000 kg each pile and for each organic waste. The piles were turned every two weeks and water was regularly added to maintain appropriate moisture level. For MSW, the composting process lasted approximately 6 months, whereas for PM and CM this process lasted about 4 months. The main soil and organic characteristics are shown in Table 1. The methodology used in the determination of the physical and chemical parameters in soil and organic wastes is described in Gómez et al. (2014). The acidic functional group contents of humic acids isolated from organic wastes are shown in Table 1. The carboxyl group content was estimated by direct potentiometric titration at pH 8, the phenolic hydroxyl group content was estimated as two times the change in charge between pH 8 and pH 10, and the total acidity as calculated by addition (Ritchie and Perdue, 2003). The molecular mass distribution of protein in the organic wastes was also determined. The proteins were extracted at pH = 9, temperature = 55 °C and time = 3 h. The protein distribution was determined by size-exclusion chromatography using an ÄKTA-purifier (GE Healthcare), using a Superdex PeptideTM 10/300GL column (Table 1). Samples were centrifuged at 12.000g for 30 min at 4 °C to remove insoluble molecules, and the supernatant was passed through a 0.2 μm filter and loaded into a 0.1 ml loop connected to an ÄKTApurifier system. The column was equilibrated, and eluted with 0.25 M Tris–HCl buffer (pH 7.0) in isocratic mode, at a flow-rate of 0.5 ml/min, and proteins/peptides were detected at 280 and 215 nm with a GE Healthcare UV900 module coupled to the elution column. The herbicide used in this experiment was flazasulfuron. The commercial formulation Terafit (flazasulfuron 25% p/p) was purchased from Syngenta (Spain). The rate applied to the soil was 0.2 kg ha−1 (recommended application rate).

• C, control soil, non-organic amended and without flazasulfuron • F, soil with flazasulfuron and non-organically amended • MSW, soil without flazasulfuron and amended with 10 t ha MSW (dry matter) (4710 kg OM ha ) • PM, soil without flazasulfuron and amended with 7.8 t ha PM (dry matter) (4710 kg OM ha ) • CM, soil without flazasulfuron and amended with 6 t ha CM (dry matter) (4710 kg OM ha ) • F + MSW, soil with flazasulfuron and amended with 10 t ha MSW (dry matter) (4710 kg OM ha ) • F + PM, soil with flazasulfuron and amended with 7.8 t ha PM (dry matter) (4710 kg OM ha ) • F + CM, soil with flazasulfuron and amended with 6 t ha CM (dry −1

−1

−1

−1

−1

−1

−1

−1

−1

−1

−1

matter) (4710 kg OM ha−1)

2.3. Soil biochemical analysis On days 5, 10, 20, 40, 80 and 120 days after the application of the herbicide to the soil and for each treatment, soil humus-enzymatic complexes were also determined. The extraction was carried out with 0.1 mol l−1 sodium pyrophosphate (pH 7.0). The extraction was performed in cold after 5 h previous sonication of a 1/10 soil/pyrophosphate mixture. The extract was separated by centrifugation at 10 000 rpm for 30 min and filtered through 0.22-mm Millipore membrane filters (microbiological filtration). Finally an extract aliquot was dialyzed against distilled water in cut molecular weight membranes of 14000 units (Visking® dialysis tube, Serva, Germany). The extraction was performed in triplicate. In the extract, the urease activity was determined by the buffered method of Kandeler and Gerber (1988), using urea as substrate. The β-glucosidase activity was determined 82

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2.6. Column leaching studies

using p-nitrophenyl-β-D-glucopyranoside as substrate (Masciandaro et al., 1994). Phosphatase activity was measured using p-nitrophenyl phosphate as substrate (Tabatabai and Bremner, 1969). Arylsulfatase activity was determined using p-nitrophenylsulfate as substrate (Tabatabai and Bremner, 1970). Soil microbial biomass was determined using the CHCl3fumigationextraction method (Vance et al., 1987). Samples of moist soil (10 g) were used, and K2SO4–extractable C was determined using dichromate digestion. Microbial biomass-C was calculated (Vance et al., 1987) using the equation:

Leaching experiments were carried out using methacrylate soil columns (30 cm length × 3.5 cm i.d.) filled with 20 cm of soil. To minimize soil losses during the experiment, glass wool plus 10 g of sea sand was placed of the bottom of the columns. The columns were handpacked with 180 g of soil, without and whit organic wastes (18 g of CM, 22.3 g of PM and 29.3 g of MSW, in order to apply the same amount of organic matter) and 10 g of sea sand were then placed on the soil surface. The columns were saturated with distilled water, allowed to drain for 24 h, and then the amount of flazasulfuron corresponding to an application rate of 1 kg ha−1 was applied to the top of the columns. The columns were leached daily with 20 mm of distilled water and the leachates were collected, centrifuged and filtered. The flazasulfuron concentration was determined by the methodology previous described on days 5, 10, 15, 20 and 30 days after the application of herbicide to soil. The leaching experiment was conducted in triplicate.

Biomass-C = 2.64EC where EC = (organic-C in K2SO4 from fumigated soil) − (organic-C in K2SO4 from non-fumigated soil). Adenosine triphosphate (ATP) was extracted from soil using the Webster et al. (1984) procedure and measured as recommended by Ciardi and Nannipieri (1990). Twenty milliliters of a phosphoric acid extractant were added to 1 g of soil, and the closed flasks were shaken in a cool bath. Then the mixture was filtered through Whatman paper and an aliquot was used to measure the ATP content by means of luciferin–luciferase assay in a luminometer.

2.7. Statistical analysis A two-ways analysis of variance (ANOVA) was performed for all parameters, considering two variables involved (incubation time and the treatments used as independent variables) using the Statgraphics Plus 2.1 software package. Data were tested for homogeneity of variance, and where differences were significant, Tukey’s test was performed for post hoc comparisons between levels within each factor, considering a significance level of P < 0.05 throughout the study. For the ANOVA, triplicate data were used for each treatment and every incubation day.

2.4. Adsorption studies For adsorption studies the treatments used were: (1) S, non-organic amended control soil (10 g of soil) (2) S + CM, soil amended with CW at rate of 10% (10 g of soil + 1 g of CM) (3) S + PM, soil amended with PM at a rate of 12.4% (10 g of soil + 1.24 g of PM) (4) S + MSW, soil amended with MSW at a rate of 16.3% (10 g of soil + 1.63 g of MSW)

3. Results 3.1. Soil biochemical properties Compared to the control soil, the humus-enzyme complexes increased significantly (p < 0.05) when the different sources of organic matter were applied to the soil (Tables 2 and 3). However, the different chemical compositions of the organic matter increased these humusenzyme complexes differently. In this sense, and at the end of the incubation period, humus-urease complex increased by 65.4% in MSWamended soil, 54.4% in PM-amended soil and 49.4% in CM-amended soil. The humus-β-glucosidase complex increased by 94.6% in MSWamended soil, followed by 93.3% and 88.4% in PM and CM-amended soils, respectively. Similarly, the humus-phosphatase and humus-arylsulfatase complexes were highest in MSW-amended soil, followed by PM and CM, respectively. When flazasulfuron was added to soil, the humus-enzyme complexes showed no variation with regard to the treatment without herbicide (Tables 2 and 3). As before, these humusenzyme complexes were highest in MSW-amended soil, followed by PM and CM, respectively. The soil microbial biomass-C showed very similar results to those obtained with humus-enzyme complexes (Table 4). Compared with the control soil, this biochemical parameter increased significantly (p < 0.05) in organically-amended soils. As above, this increase depended on the chemical composition of the organic material applied. Thus, compared to the control treatment and at the end of the incubation period, soil microbial biomass-C increased significantly by 77.7%, 73.1% and 72.1% in soils amended with MSW, PM and CM, respectively. When the herbicide was applied to the soil, microbial biomass-C showed a similar evolution with respect to the flazasulfuronfree treatments The evolution of ATP in soil was also very similar (Table 4). The highest ATP values were found in MSW-amended soil, followed by PM and CM, respectively. The application of the herbicide to the soil did not change these values.

Flazasulfuron sorption was determined according to Cabrera et al. (2009) criteria. Triplicate samples (5 g) of the unamended and organic amended soil (S, S + CM, S + PM, S + MSW) were treated with 10 ml of flazasulfuron (50%:50%, v/v) solution (initial concentrations, Ci, ranging from to 50 μM in 0.01 CaCl2). Previously, it was determined that equilibrium was reached in less than 24 h, and that no measurable degradation occurred during this period. Equilibrium concentrations (Ce) in the supernatants were determined by HPLC. Sorption isotherms were fitted to Freundlich equation (Cs = Kf x Ce1/nf) and sorption coefficients Kf and 1/nf were calculated.

2.5. Herbicide analysis Soil flazasulfuron was determined at days 5, 10, 20, 40, 80 and 120 after the application of the herbicide to the soil. Flazasulfuron was extracted from soil using the Anastassiades et al. (2003) method. Herbicide was extracted with a mixture of triphenyl phosphate and acetonitrile. Once shaken and centrifuged, magnesium sulfate to the supernatant which was then stirred and centrifuged again. The supernatant was concentrated and the dried residue was recomposed with 1 ml of methanol:H2O (1:1). Flazasulfuron was determined using a tandem mass spectrometer with positive electrospray, where the chromatographic conditions were as follows: Collision gas: Argon, Gas cone desolvation and nebulization: Nitrogen, Source temperature: 120 °C; desolvation temperature: 450 °C; Column oven: 50 °C; Autosampler: 10 °C, flow rate: 0.4 ml/min; injection volume 7 μl; gradient: A = water with 0.1% formic acid. B = methanol with 0.1% formic acid.

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Table 2 Evolution of humus-urease and β-glucosidase activities (mean ± standard error) in soil treatments. Incubation days 5

10

20

40

80

120

C F MSW PM CM F + MSW F + PM F + CM

Urease activity (μmol NH4+ g−1 d−1) 0.42aa ± 0.09 0.39a ± 0.06 0.45a ± 0.07 0.43a ± 0.09 1.16c ± 0.13 1.23c ± 0.10 0.93b ± 0.10 0.93b ± 0.14 0.79b ± 0.11 0.78b ± 0.13 1.20c ± 0.19 1.22c ± 0.11 0.95bc ± 0.17 0.94bc ± 0.14 0.76b ± 0.14 0.75b ± 0.10

0.45a ± 0.08 0.39a ± 0.09 1.19c ± 0.09 0.95bc ± 0.13 0.82b ± 0.10 1.20c ± 0.17 0.94bc ± 0.18 0.83b ± 0.12

0.43a ± 0.10 0.46a ± 0.04 1.24c ± 0.12 0.94bc ± 0.08 0.86b ± 0.11 1.25c ± 0.13 0.95bc ± 0.16 0.82b ± 0.16

0.46a ± 0.05 0.42a ± 0.07 1.28c ± 0.09 0.98bc ± 0.11 0.84b ± 0.13 1.30c ± 0.16 0.97bc ± 0.11 0.86b ± 0.09

0.46a ± 0.08 0.47a ± 0.10 1.33c ± 0.14 1.01bc ± 0.16 0.91b ± 0.14 1.35c ± 0.11 1.03bc ± 0.16 0.89b ± 0.14

C F MSW PM CM F + MSW F + PM F + CM

β-glucosidase activity (μmol PNP g−1 d−1) 0.023aa ± 0.005 0.021a ± 0.007 0.026a ± 0.008 0.022a ± 0.009 0.469c ± 0.016 0.472c ± 0.013 0.384bc ± 0.014 0.379bc ± 0.018 0.201b ± 0.017 0.209b ± 0.011 0.471c ± 0.019 0.473c ± 0.022 0.385bc ± 0.020 0.382bc ± 0.016 0.203b ± 0.024 0.202b ± 0.025

0.024a ± 0.008 0.022a ± 0.005 0.469c ± 0.019 0.382bc ± 0.024 0.207b ± 0.019 0.472c ± 0.022 0.388bc ± 0.017 0.205b ± 0.023

0.019a ± 0.005 0.021a ± 0.005 0.479c ± 0.021 0.389bc ± 0.017 0.214b ± 0.014 0.480c ± 0.026 0.386bc ± 0.014 0.216b ± 0.018

0.022a ± 0.005 0.023a ± 0.007 0.482c ± 0.016 0.391bc ± 0.021 0.222b ± 0.018 0.490c ± 0.024 0.394bc ± 0.020 0.221b ± 0.017

0.026a ± 0.006 0.022a ± 0.008 0.481c ± 0.017 0.390bc ± 0.018 0.225b ± 0.023 0.501c ± 0.019 0.398bc ± 0.024 0.227b ± 0.016

PNP: p-nitrophenol. a Columns followed by the same letter(s) are not significantly different according to the Tukey test (p > 0.05).

soils with respect to non-organically-amended soil. For organicallyamended soils, the 1/nf coefficient was highest in the MSW-amended soil, followed by PM and CM, respectively.

3.2. Sorption studies Sorption isotherms of flazasulfuron on soil, soil + CM, soil + PM and soil + MSW are shown in Fig. 2. The results indicated that, compared to non-organically-amended soil, sorption of flazasulfuron on organically-amended soils increased. Moreover, herbicide sorption was influenced by the chemical composition of the organic matter. In this respect, herbicide sorption was highest in the MSW amendment, followed by the PM and CM amendments, respectively. Sorption isotherms were fit to the Freundlich equation and sorption coefficients Kf and 1/nf were calculated (Table 5). The results indicated that Kf values significantly increased in organically-amended soils with respect to non-organically-amended soils. However, flazasulfuron sorption increased by a factor of 6.7 upon amendment with MSW, whereas for PM and CM, the factor increased by 5.8 and 4.98, respectively. Also, the 1/nf coefficients significantly decreased in organically-amended

3.3. Evolution of flazasulfuron in soil Fig. 1 shows the evolution of flazasulfuron in soils. The results show a progressive degradation of the herbicide in the soil throughout the experiment. The application of organic matter significantly decreased the soil herbicide concentration, probably due to flazasulfuron sorption by organic matter. This decrease varied, depending on the type of organic matter applied. In this regard, the concentration of herbicide was lowest in MSW-amended soils, followed by PM and CM-amended soils, respectively.

Table 3 Evolution of humus-phosphatase and arylsulfatase activities (mean ± standard error) in soil treatments. Incubation days 5

10

20

40

80

120

C F MSW PM CM F + MSW F + PM F + CM

Phosphatase activity (μmol PNP g−1 d−1) 0.59aa ± 0.04 0.60a ± 0.07 0.60a ± 0.05 0.61a ± 0.05 6.9c ± 1.0 7.2c ± 1.3 4.0b ± 0.7 4.3bc ± 0.9 2.9b ± 0.4 3.0b ± 0.7 6.7c ± 1.2 6.9c ± 1.6 4.3bc ± 0.9 4.2bc ± 0.7 3.1b ± 0.6 3.1b ± 0.5

0.61a ± 0.03 0.60a ± 0.04 7.4c ± 1.2 4.3bc ± 0.6 2.9b ± 0.5 6.8c ± 1.5 4.4bc ± 1.0 3.3b ± 0.7

0.60a ± 0.04 0.62a ± 0.06 7.4c ± 1.5 4.6bc ± 0.9 3.2b ± 0.6 7.0c ± 1.7 4.8bc ± 1.2 3.5b ± 0.9

0.62a ± 0.07 0.65a ± 0.04 7.5c ± 1.6 5.0bc ± 1.0 3.4b ± 0.8 7.2c ± 1.4 5.0bc ± 0.9 3.7b ± 0.3

0.64a ± 0.06 0.65a ± 0.08 7.6c ± 1.5 5.3bc ± 0.9 4.0b ± 0.7 7.5c ± 1.3 5.4bc ± 1.1 4.2b ± 0.6

C F MSW PM CM F + MSW F + PM F + CM

Arylsulfatase activity (μmol PNF g−1 d−1) 0.24aa ± 0.2 0.25a ± 0.3 0.25a ± 0.2 0.26a ± 0.2 2.9bc ± 0.5 3.1c ± 0.4 1.9b ± 0.1 1.8b ± 0.2 1.1b ± 0.2 1.3b ± 0.2 3.0c ± 0.5 3.0c ± 0.4 2.0bc ± 0.2 2.2bc ± 0.3 1.2b ± 0.2 1.5b ± 0.3

0.27a ± 0.4 0.26a ± 0.3 3.3c ± 0.6 2.0b ± 0.2 1.3b ± 0.1 3.4c ± 0.4 2.4bc ± 0.2 1.5b ± 0.2

0.27a ± 0.3 0.25a ± 0.3 3.3c ± 0.4 2.2bc ± 0.3 1.5b ± 0.2 3.5c ± 0.3 2.4bc ± 0.4 1.4b ± 0.3

0.28a ± 0.4 0.27a ± 0.4 3.6c ± 0.5 2.2bc ± 0.3 1.7b ± 0.3 3.7c ± 0.5 2.6bc ± 0.3 1.9b ± 0.4

0.28a ± 0.4 0.27a ± 0.2 4.0c ± 0.5 2.6bc ± 0.4 1.9b ± 0.3 4.2c ± 0.6 2.9bc ± 0.5 2.1b ± 0.4

PNP: p-nitrophenol; PNF: p-nitrophenyl. a Columns followed by the same letter(s) are not significantly different according to the Tukey test (p > 0.05).

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Table 4 Evolution of microbial biomass-C and ATP (mean ± standard error) in soil treatments. Incubation days 5

10

20

40

C F MSW PM CM F + MSW F + PM F + CM

Microbial biomass-C (μg C g−1 dry soil) 108aa ± 12 99a ± 9 103a ± 8 107a ± 11 423c ± 27 431c ± 18 370b ± 24 375b ± 33 352b ± 26 359b ± 31 425c ± 33 436c ± 21 367b ± 28 363b ± 25 359b ± 21 361b ± 35

106a 100a 441c 384b 372b 447c 374b 369b

C F MSW PM CM F + MSW F + PM F + CM

ATP (ng g−1 soil) 215aa ± 12 218a ± 10 455c ± 31 389b ± 27 342b ± 27 460c ± 27 392b ± 29 345b ± 22

212a ± 9 216a ± 12 479c ± 34 403bc ± 34 350b ± 25 483c ± 37 398b ± 27 352b ± 19

a

219a ± 15 214a ± 13 462c ± 37 395b ± 30 345b ± 30 465c ± 33 400bc ± 36 344b ± 28

± ± ± ± ± ± ± ±

13 11 39 28 22 35 36 30

110a 114a 460c 392b 380b 453c 380b 375b

± ± ± ± ± ± ± ±

13 12 32 20 25 40 30 27

217a ± 11 219a ± 15 493c ± 40 411bc ± 28 362b ± 20 498c ± 44 419bc ± 34 359b ± 31

80

120

112a ± 10 109a ± 9 479c ± 26 404bc ± 36 390b ± 30 474c ± 36 391b ± 37 384b ± 24

111a ± 12 115a ± 14 498c ± 40 413bc ± 31 398b ± 28 503c ± 34 407bc ± 31 393b ± 33

220a ± 13 216a ± 8 510c ± 38 423bc ± 30 371b ± 33 518c ± 31 430bc ± 22 368b ± 26

218a ± 14 217a ± 16 529c ± 42 439bc ± 35 385b ± 24 532c ± 45 442bc ± 30 383b ± 33

Columns followed by the same letter(s) are not significantly different according to the Tukey test (p > 0.05).

Table 5 Freundlich sorption coefficients Kf and 1/nf (mean ± standard error) for flazasulfuron in unamended and organic amended soils.

S S + MSW S + PM S + CM

Kf

1/nf

R2

5.2aa ± 0.9 34.9c ± 3.4 30.1b ± 3.6 25.6b ± 2.3

0.93aa ± 0.07 0.75c ± 0.06 0.80b ± 0.05 0.84b ± 0.04

0.989 0.979 0.991 0.98477

a Columns followed by the same letter(s) are not significantly different according to the Tukey test (p > 0.05).

3.4. Leaching experiments Fig. 3 shows the breakthrough curves (BTCs) of flazasulfuron applied to unamended and organically-amended soil columns. Flazasulfuron applied to organically-amended soils resulted in lower maximum concentrations in the leachates, as compared with herbicide concentrations in the unamended soil. The maximum concentration of flazasulfuron in leachates was reduced from 8.9 μM for the unamended soil, to 3.5, 5.4, 6.9 μM for the MSW, PM and CM-amended soils. In

Fig. 2. Flazasulfuron sorption isotherms in unamended and organically-amended soils. Symbols are experimental data points, whereas lines are the Freundlick-fit sorption isotherms.

organic treatments, significant differences were found between the leachates herbicide for MSW and CM-amended soils. In this respect, and compared to CM-amended soils, the flazasulfuron leachates decreased

Fig. 1. Evolution of flazasulfuron (mean ± standard error) in soils treatments. Data are the means of three samples. Columns followed by the same letter(s) are not significantly differentaccording to the Tukey test (p > 0.05).

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Fig. 3. Flazasulfuron breakthrough curves (BTCs) (mean ± standard error) in soils treatments. Data are the means of three samples. Columns followed by the same letter(s) are not significantly different according to the Tukey test (p > 0.05). (A) relative BTCS (B) cumulative BTCs

are reports, however, indicating that sulfonylureas with a similar chemical composition, such as flupyrsulfuron-methyl, showed high field persistence (a 100-day half-life) (Rouchaud et al., 1999). On the other hand, there are also sulfonylureas with pyridine rings such as rimsulfuron that which degrade rapidly (with a half-life of 7.5-24 days) (Schneiders et al., 1993; Martins and Mermoud, 1999). The application of organic wastes to unpolluted significantly increased the biochemical properties. Soil microorganisms degrade organic matter through the production of extracellular enzymes, explaining the increase in the biochemical parameters after applying organic wastes to the soil (Ferreras et al., 2006; Tejada and González, 2009; Tejada et al., 2010a,b). However, the increase of biochemical properties was higher in the MSW than in PM and CM-amended soil. According to Tejada et al. (2010a,b), the organic matter with higher fulvic than humic acids contents is degraded more rapidly in the soil, promoting more positively the soil’s biochemical properties. On the other hand, MSW had the highest content of low molecular weight proteins, followed by PM and CM. In general terms, soil microorganisms absorb low molecular weight proteins more easily, something which also contributes to an increase in the proliferation of soil microorganisms and, therefore, an increase in soil biochemical properties (Vasileva-Tonkova et al., 2007). Since applying flazasulfuron does not affect the biochemical properties of soil, applying organic matter to the soil with the herbicide resulted in the treated soil behaving and evolving similarly to an herbicide-free organic soil. However, the flazasulfuron sorption iso-

by 40.3% in MSW. 4. Discussion Our results indicated that flazasulfuron herbicide did not cause changes in soil biochemical properties. These results are in agreement with those obtained for other sulfonylureas applied to the soil. In this respect, Dinelli et al. (1998) found no detrimental effects of trialsulfuron, rimsulfuron and primisulfuron methyl on soil respiration and dehydrogenase activity. Furthermore, Malkomes (2006) found no effects on soil microorganisms in a soil after applying amidosulfam and tribenuron. However, Ismail et al. (1998) found a negative effect on the amylase, urease and protease activities after adding metsulfuronmethyl to two soils. The chemistry, degradation and the mode of action of sulfonylureas has been discussed in many papers (Blair and Martin, 1988; Brown and Cotterman, 1999; Sarmah, and Sabadie, 2002). In this respect, the literature indicates that sulfonylureas can be degraded by the action of soil microorganisms or by chemical hydrolysis (Sarmah and Sabadie, 2002). Since flazasulfuron did not affect soil biochemical properties, this suggests that degradation of this herbicide can occur by processes of chemical hydrolysis. Flazasulfuron showed a high persistence in soil. Flazasulfuron is a sulfonylurea that is characterized by a pyridine ring and we have not found information concerning this herbicide’s degradation in soil. Therefore, we must be wary when discussing its degradation. There 86

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Abatement kinetics of 30 sulfonylurea herbicide residues in water by photocatalytic treatment with semiconductor materials. J. Environ. Manag. 130, 361–368. Ferreras, L.E., Gomez, E., Toresani, S., Firpo, I., Rotondo, R., 2006. Effect of organic amendments on some physical, chemical and biological properties in a horticultural soil. Biores. Technol. 97, 635–640. Franco-Andreu, L., Gómez, I., Parrado, J., García, C., Hernández, T., Tejada, M., 2016. Behavior of two pesticides in a soil subjected to severe drought. Effects on soil biology. Appl. Soil Ecol. 105, 17–24. Gómez, I., Rodríguez-Morgado, B., Parrado, J., García, C., Hernández, T., Tejada, M., 2014. Behavior of oxyfluorfen in soils amended with different sources of organic matter. Effects on soil biology. J. Hazard. Mate. 273, 207–214. Hiller, E., Tatarková, V., Šimonovičova, A., Bartal, M., 2012. Sorption, desorption, and degradation of (4-chloro-2-methylphenoxy)acetic acid in representative soils of the Danubian Lowland, Slovakia. Chemosphere 87, 437–444. Iglesias, A., López, R., Gondar, D., Antelo, J., Fiol, S., Arce, F., 2010. Adsorption of MCPA on goethite and humic acids-coated goethite. Chemosphere 78, 1403–1408. Ismail, B.S., Yapp, K.F., Omar, O., 1998. Effects of metsulfuron-methyl on amylase, urease, and protease activities in two soils. Aust. J. Soil Res. 36, 449–456. Kandeler, E., Gerber, G., 1988. Short-term assay of soil urease activity using colorimetric determination of ammonium. Biol. Fertil. Soils 6, 68–72. López-Piñero, A., Peña, D., Albarrán, A., Sánchez-Llerena, J., Becerra, D., 2013. 2013. Behavior of MCPA in four intensive cropping soils amended with fresh composted, and aged olive oil mill waste. J. Contam. Hydrol. 152, 137–146. Li, L.J., Han, X.Z., 2016. Changes of soil properties and carbon fractions after long-term application of organic amendments in Mollisols. Catena 143, 140–144. Malkomes, H.P., 2006. Einfluss von zwei Sulfonylharnstoff-Herbiziden und einem Vergleichsmittel auf mikrobielle Aktivitäten im Boden, Nachrichtenbl. Deut. Pflanzenschutzd. 58, S269–273. Martins, J.M.F., Mermoud, M., 1999. Transport of rimsulfuron and its metabolites in soil columns. Chemosphere 38, 601–616. Masciandaro, G., Ceccanti, B., García, C., 1994. Anaerobic digestion of straw and piggery wastewaters: II. Optimization of the process. Agrochimica 38, 195–203. Masciandaro, G., Macci, C., Doni, S., Ceccanti, B., 2012. Role of humo-enzyme complexes in restoring of soil ecosystems. In: Trasar-Cepeda, C., Hernández, T., García, C., Rad, C., González-Carcedo, S. (Eds.), Soil Enzymology in the Recycling of Organic Wastes and Environmental Restoration. Springer, Heidelberg, Dordrecht, London, New York, pp. 21–36. Parihar, C.M., Yadav, M.R., Jat, S.L., Singh, A.K., Kumar, B., Pradhan, S., Chakraborty, D., Jat, M.L., Jat, R.K., Saharawat, Y.S., Yadav, O.P., 2016. 2016. Long term effect of conservation agriculture in maize rotations on total organic carbon: physical and biological properties of a sandy loam soil in north-western Indo-Gangetic Plains. Soil Till. Res. 161, 116–128. Ritchie, J.D., Perdue, E.M., 2003. Proton-binding study of standard and reference fulvic acids, humic acids, and natural organic matter. Geochem. Cosmochim. Acta 67, 85–96. Rouchaud, J., Neus, O., Cools, K., Bulcke, R., 1999. Flupyrsulfuron soil dissipation and mobility in winter wheat crops. J. Agric. Food Chem. 47, 3872–3878. Sørensen, S.R., Schultz, A., Jacobsen, O.S., Aamand, J., 2006. Sorption, desorption and mineralization of the herbicides glyphosate and MCPA in samples from two Danish soil and subsurface profiles. Environ. Pollut. 141, 184–194. Sarmah, A.K., Sabadie, J., 2002. Hydrolysis of sulfonylurea herbicides in soils and aqueous solutions: a review. J. Agric. Food Chem. 50, 6253–6265. Schneiders, G.E., Koeppe, M.K., Naidu, M.V., Horne, P., Brown, A.M., Mucha, C.F., 1993. Fate of rimsulfuron in the environment. J. Agric. Food Chem. 41, 2404–2410. Soil Survey Staff, 1987. Keys to soil taxonomy. SMSS Technical Monograph No. 6, 3rd edn. Soil Survey Staff, New York, pp. 1987. Tabatabai, M.A., Bremner, J.M., 1969. Use of p-nitrophenol phosphate in assay of soil phosphatase activity. Soil Biol. Biochem. 1, 301–307. Tabatabai, M.A., Bremner, J.M., 1970. Arylsulfatase activity of soils. Soil Sci. Soc. Am. Proc. 34, 225–229. Tejada, M., Benítez, C., 2011. Organic amendment based on vermicompost and compost: differences on soil properties and maize yield. Waste Manag. Res. 29, 1185–1196. Tejada, M., González, J.L., 2009. Application of two vermicomposts on a rice crop: effects on soil biological properties and rice quality and yield. Agron. J. 101, 336–344. Tejada, M., Gómez, I., del Toro, M., 2001. Use of organic amendments as a bioremediation strategy to reduce the bioavailability of chlorpyrifos insecticide in soils. Effects on soil biology. Ecotoxicol. Environ. Saf. 74, 2075–2081. Tejada, M., García-Martínez, A., Gómez, I., Parrado, J., 2010a. Application of MCPA herbicide on soils amended with biostimulants: short-time effects on soil biological properties. Chemosphere 80, 1088–1094. Tejada, M., Gómez, I., Hernández, T., García, C., 2010b. Utilization of vermicomposts in soil restoration: effects on soil biological properties. Soil Sci. Soc. Am. J. 74, 525–532. Tejada, M., 2009. Evolution of soil biological properties after addition of glyphosate, diflufenican and glyphosate + diflufenican herbicides. Chemosphere 76, 365–373. Vance, E.D., Brookes, P.C., Jenkinson, D.S., 1987. An extraction method for measuring soil microbial biomass C. Soil Biol. Biochem. 19, 703–707. Vasileva-Tonkova, E., Nustorova, M., Gushterova, A., 2007. New protein hydrolysates from collagen wastes used as peptone for bacterial growth. Curr. Microbiol. 54, 54–57. Webster, J., Hampton, G., Leach, F., 1984. ATP in soil: a new extractant and extraction procedure. Soil Biol. Biochem. 16, 335–342.

therms and Freundlich sorption coefficients suggested that organic matter plays a fundamental role in the sorption of the herbicide, probably as a result of the humic substances containing several major functional groups, such as carboxyl, phenolic, alcohol and carbonyl (Cox et al., 2001; Tejada et al., 2001; Dolaptsoglou et al., 2007). Tejada et al. (2001) found that the adsorption of chlorpyrifos insecticide in soils amended with organic wastes increased when these wastes contained greater amounts of humic acid. Therefore, the adsorption of insecticide probably increased in line with the humic acid content of the organic waste applied to the soil. In this experiment, flazasulfuron herbicide adsorption was greatest in soils amended with organic matter with a higher content of humic acids. This conclusion is also supported by the results of leaching, where the contents of herbicide leachates were lower in organically-amended soil whose organic amendment had a higher humic acid content. 5. Conclusions It can be concluded that flazasulfuron herbicide did not affect the biochemical properties of the experimental soil. This aspect is of great interest since it shows that the degradation flazasulfuron on soil might not depend on the activity of microorganisms, but rather on processes of chemical hydrolysis. The application of organic matter to the soil is good environmental practice because it decreases the concentration of flazasulfuron in leachates. However, the beneficial effect depended on the organic matter’s chemical composition. The herbicide leachates were higher in MSW than in PM or CM-amended soils. These results indicated that adding organic materials with a higher humic-acid concentration may be considered a good strategy for decreasing environmental flazasulfuron pollution. References Albarrán, A., Celis, R., Hermosín, M.C., López-Piñero, A., Cornejo, J., 2004. Behavior of simazine in soil amended with the final residue of the olive-oil extraction process. Chemosphere 54, 717–724. Anastassiades, M., Lehotay, S.J., Stajnbaher, D., Shenck, F.J., 2003. Fast and easy multiresidue method employing extraction/partitioning and dispersive solid phase extraction for the determination of pesticide residues in produce. JAOAC Int. 86, 412–431. Aranda, V., Macci, C., Peruzzi, E., Masciandaro, G., 2015. Biochemical activity and chemical-structural properties of soil organic matter after 17 years of amendments with olive-mill pomace co-compost. J. Environ. Manag. 147, 278–285. Bastida, F., Kandeler, E., Moreno, J.L., Ros, M., García, C., Hernández, T., 2008. Application of fresh and composted organic wastes modifies structures: size and activity of soil microbial community under semiarid climate. Appl. Soil Ecol. 40, 318–329. Beyer Jr, E.M., Duffy, M.J., Hay, J.V., Schluete, D.D., 1988. Sulfonylurea herbicides. In: Kearney, P.C., Kaufman, D.D. (Eds.), Herbicides: Chemistry, Degradation and Mode of Action. Marcel Dekker, New York, pp. 117–190. Blair, A.M., Martin, T.D., 1988. A review of the activity, fate and mode of action of sulfonylurea herbicides. Pestic. Sci. 22, 195–219. Brown, H.M., Cotterman, J.C., 1999. Recent advances in sulfonylurea herbicides. In: Stetter, J. (Ed.), Herbicides Inhibiting Branched-Chain Amino Acid Biosynthesis. Springer, Berlin, Heidelberg, pp. 47–81. Brown, H.M., 1990. Mode of action, crop selectivity, and soil relations of the sulfonylurea herbicides. Pestic. Sci. 29, 263–281. Cabrera, A., Cox, L., Fernández-Hernández, A., García-Ortiz Civantos, C., Cornejo, J., 2009. Field appraisement of olive mills solid waste application in olive crops: effect on herbicide retention. Agric. Ecosyst. Environ. 132, 260–266. Ciardi, C., Nannipieri, P., 1990. A comparison of methods for measuring ATP in soil. Soil Biol. Biochem. 22, 725–727. Cox, L., Cecchi, A., Celis, R., Hermosin, M.C., Koskinen, W.C., Cornejo, J., 2001. Effect of exogenous carbon on movement of simazine and 2,4-D in soils. Soil Sci. Soc. Am. J. 65, 1688–1695. Dinelli, G., Vicari, A., Accinell, C., 1998. Degradation and side effects of three sulfonylurea herbicides in soil. J. Environ. Qual. 27, 1459–1464. Dolaptsoglou, Ch., Karpouzas, D.G., Menkissogh-Spirondi, U., Eleftherohorinos, I., Voudrias, E.A., 2007. Influence of different organic amendments on the degradation, metabolism, and adsorption of terbuthylazine. J. Environ. Qual. 36, 1793–1802. Fenoll, J., Sabater, P., Navarro, G., Vela, N., Pérez-Lucas, G., Navarro, S., 2013.

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